Thermal upgrade will improve the thermal efficiency of your glass and increase the overall energy rating, as well as reduce the 'U' value
The following upgrades will be applied to your glass:
1) Argon gas filled panes (usually air)
2) Warm edge spacer bars (usually silver)
3) Low E (emissivity) film
You can find out more about triple glazed windows and doors on our
Energy ratings & 'U' values page
Some further benefits of upgrading your glass